The invention relates to a vulcanization mold for the manufacture of technical rubber products, in particular for the manufacture of vehicle tires, comprising a plurality of vent bores in each of which a blocking member is mounted which at least substantially blocks the penetration of (tire) blank material, the blocking member having a central body which can be fixed in a force-transmitting manner in the respective vent bore, and also a sealing part coupled to the central body and having a surface region disposed toward the inner side of the mold which is provided with at least one aperture and which, together with the central body, forms at least one angled flow path for the air following the aperture. Furthermore, the invention relates to a blocking member for use in such a vulcanization mold.
A vulcanization mold of the above named kind is known from the international application PCT/EP99/05323. This vulcanization mold has proven itself in practice and makes possible, for example, the manufacture of spue free vehicle tires, i.e. tires without bristles or spues at positions corresponding to the positions of vents in the tire mold. It is noted that the bristles or spues are sometimes referred to as sprues or shoots.
It is the principal object of the present invention to further improve the proven solution described above, and indeed in particular with respect to the venting capability and the mechanical fixation of the blocking members in the respective receiving bores.
Starting from the initially mentioned vulcanization mold, the above object is essentially satisfied, in accordance with the present invention, in that the central body is fixed in the respective vent bore, on the one hand, by clamping ribs provided at its outer periphery which cooperate with the bore wall and, on the other hand, by blocking elements which are formed on spring limbs of the sealing part provided for the coupling to the central body and which have a barb function with respect to the bore wall in the direction of the inner side of the mold.
In this manner a stable seating of the blocking members in the vent bores is achieved using constructionally simple measures such that, on removal of the respectively manufactured rubber product from the mold, there is no risk of the blocking members being fully or partly pulled out of the vent bores. The mounting of the blocking members is sufficiently stable that there is no risk of the blocking members being fully or partly pulled out of the vent bores even if some rubber material should penetrate into the blocking member and be fully vulcanized while engaging behind part regions of the blocking member. It is of special importance here that the technical measures necessary to ensure this secure hold can be realized very simply and at a favorable cost and nevertheless do not make the introduction of the blocking members into the corresponding vent bores more difficult. Furthermore, the design has the advantage that the blocking members can still be readily exchanged despite the stable seating in the vent bores.
Particularly advantageous embodiments of the subject matter of the invention are recited in the dependent claims and will be explained in more detail in connection with the description of the embodiment with reference to the accompanying drawings.